Conventionally, there has been known a remote controlled load management system, as shown in FIG. 14, for controlling loads, for instance, illumination loads or lamps L (see, e.g., Japanese Patent Laid-open Publication No. 2003-111154 and U.S. Pat. No. 6,888,472 B2). Such a remote controlled load management system includes a central controller 100, a plurality of switch terminals 101 and a plurality of load terminals 102, which are connected for intercommunications with each other through a two-wire transmission line Ls.
The load terminals 102 include a normal type 102a for turning on and off the lamps and a dimmer type 102c capable of dimming the lamps L. Each of the load terminals 102a and 102c is provided with load ports 122 for connection with up to four lamps L and with a line port 24 for connection with the transmission line Ls. Each load terminal includes an intelligent section having load addresses respectively allocated to the load ports, i.e., the loads connected thereto, and includes relays for turning on and off the loads in response to a command transmitted from the central controller 100. The dimmer type load terminal 102c is added with a dimmer which provides a dimmer command for varying illumination power being fed to the lamp L in response to the command from the central controller 100. Further, each load terminal is given a function of transmitting back to the central controller a status signal indicative of a condition of the lamp.
The switch terminals 101 includes three types, one being a normal type 111a for turning on and off the associated lamps individually, another being a pattern type 101b for turning on and off a group of the lamps in accordance with a predetermined pattern, and the rest being a dimmer type 101c for dimming the lamp. The pattern type switch terminal 101b is utilized to actuate in accordance with a selected pattern of control for the lamps. For this purpose, the switch terminal of this type is associated with the selected lamps and the selected control method. Such relation is stored in the central controller 100. Each of the switch terminals includes at least one switch Sa or Sb which is given individual switch addresses, each being associated with one or more loads, i.e., the load addresses at the central controller 100 such that the load or loads are actuated by the manipulation of the switch. That is, each switch terminal has an intelligent function of transmitting an event signal indicative of the switch being manipulated followed by the switch address of the switch and a particular one of control codes assigned to the switch as indicative of the manner of actuating the lamp or lamps.
The central controller 100 which governs the whole operation of the system and has an address table which relates each of the switches addressed to at least one load address, and a control table relating each of the control codes to a control method for operating the lamp or lamps. The central controller 100 generates and regularly transmits a time division multiplex signal Vs to the switch terminals 101 and the load terminals 102 via the transmission line Ls. As shown in FIG. 15, the signal Vs is a pulse modulated signal having an amplitude of ±24 V and includes a synchronous sign SY indicative of a start of the signal transmission, a mode data MD indicating a mode of controlling the load terminals or the switch terminals, an address data AD describing the address designating the lamp and the switch, a control data CD describing the control method, a check sum data CS for checking a transmission error, and a response waiting slot WT for receiving a response from the switch terminal or the load terminal. The mode data MD includes a control mode for controlling the lamp or lamps, a polling mode, a polling-interrupted mode initiated by the manipulation of the switch, i.e., the event signal from the switch terminal, and a supervision mode for supervising the status of the lamp or lamps.
When the switch terminal 101 or the load terminal 102 whose address coincides with the address given in the address data AD, the terminal responds to operate in a manner as required in the control data CD and to send back a response signal within the response waiting slot WT when so required. The response signal is responsible for transmitting the switch or load address, the control code, and the status information of the switch or the lamp, and is realized by a level-shifted signal that is a combination of high and low current level appearing between the two wires of the transmission line.
In operation, the central controller 100 is normally set into a polling mode to query whether any one of the switch terminals 101 issues an event signal as a result of the switch being manipulated. The event signal is issued from the switch terminal as an interruption signal VINT in synchronous with the synchronous sign SY at the start of the signal Vs, as shown in FIG. 15. Under this condition, the switch terminal 101 sets an interruption flag so as to be prepared for data transfer to and from the central controller 100. Upon acknowledging the interruption signal VINT or the event signal from the switch terminal 101, the central controller 100 is switched into the polling-interrupted mode in order to receive the switch address issuing the event signal as well as the control code within the response waiting slot WT. After receiving the switch address, the central controller 100 references the address table to locate the load address of the destined lamp or loads associated with the switch address. Then, the central controller 100 is set into the supervision mode in order to inquire the status of the destined lamp. In this response, the load terminal 102 connected to the destined lamp or lamps sends back the status information of the lamp to the central controller 100 which in turn transmits a confirmation signal to the switch terminal 101 and references the control table with the help of the status information of the lamp so as to obtain the control method as intended by the control code for operating lamp. Then, the central controller 100 transmits a control signal indicative of the load address and the control method to the corresponding load terminal 102 in order to actuate the lamp in the manner defined by the control method. Thereafter, the load terminal 102 sends a signal indicating the result of the control, thereby completing the requested control initiated by the event signal from the switch terminal 101.
Meanwhile, there is a case where the remote controlled load management system includes a programmable timer unit 105 for performing a load control (timer control) by automatically turning on/off the illumination loads L at preset times instead of turning on/off the illumination loads L through the manipulation of the normal type switch terminal 101a or the pattern type switch terminal 101b. The programmable timer unit 105 stores therein a program designating ON/OFF timings of the load control for each day of each week and control details, such as individual control, group control and pattern control, compares the set time data of the program with current time data, and outputs a no-voltage contact signal by opening/closing the internal output relays when the two time data coincide with each other. The input terminals of contact input terminals 106 are respectively connected to a plurality of contact signal output terminals of the programmable timer unit 105, and the contact input terminals 106 send monitoring data based on a contact signal outputted from the programmable timer unit 105 to the central controller 100, so that the central controller 100 sends control data based on the monitoring data to the load terminals 102, thereby performing the load control in accordance with the control details of the program at set times. Furthermore, a remote control transformer 107 is connected to the programmable timer unit 105 and the contact input terminal 106. The remote control transformer 107 drops the alternating voltage of, e.g., 100 V to 24 V, and the dropped voltage is supplied as operation voltage to the programmable timer unit 105 and the contact input terminal 106.
In case of automatically turning off the illumination loads L by using the programmable timer unit 105 as described above, however, a security concern may be raised when all of the illumination loads L are turned off at a set time. Accordingly, there is required a function of turning off and on the illumination loads L and then completely turning them off after a specified time period before the illumination loads L are turned off at a set time, so that the lighting of the illumination loads L can be extended for the specified time period through the switch manipulation or the like. While the aforementioned load terminals 102 can turn off the illumination loads L by driving the relays after a predetermined delay time (corresponding to the specified time period) at the time of receiving control data related to extinction from the central controller 100, the load terminals 102 immediately turn on the illumination loads L when they receive control data related to lighting from the central controller 100 during the delay time, so that it is impossible to extend the delay time and turn off the illumination loads L after the corresponding delay time.